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  <section id="module-reprlib">
<span id="reprlib-alternate-repr-implementation"></span><h1><a class="reference internal" href="#module-reprlib" title="reprlib: Alternate repr() implementation with size limits."><code class="xref py py-mod docutils literal notranslate"><span class="pre">reprlib</span></code></a> — Alternate <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> implementation<a class="headerlink" href="#module-reprlib" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.9/Lib/reprlib.py">Lib/reprlib.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-reprlib" title="reprlib: Alternate repr() implementation with size limits."><code class="xref py py-mod docutils literal notranslate"><span class="pre">reprlib</span></code></a> module provides a means for producing object representations
with limits on the size of the resulting strings. This is used in the Python
debugger and may be useful in other contexts as well.</p>
<p>This module provides a class, an instance, and a function:</p>
<dl class="class">
<dt id="reprlib.Repr">
<em class="property">class </em><code class="sig-prename descclassname">reprlib.</code><code class="sig-name descname">Repr</code><a class="headerlink" href="#reprlib.Repr" title="Permalink to this definition">¶</a></dt>
<dd><p>Class which provides formatting services useful in implementing functions
similar to the built-in <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a>; size limits for  different object types
are added to avoid the generation of representations which are excessively long.</p>
</dd></dl>

<dl class="data">
<dt id="reprlib.aRepr">
<code class="sig-prename descclassname">reprlib.</code><code class="sig-name descname">aRepr</code><a class="headerlink" href="#reprlib.aRepr" title="Permalink to this definition">¶</a></dt>
<dd><p>This is an instance of <a class="reference internal" href="#reprlib.Repr" title="reprlib.Repr"><code class="xref py py-class docutils literal notranslate"><span class="pre">Repr</span></code></a> which is used to provide the
<a class="reference internal" href="#reprlib.repr" title="reprlib.repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> function described below.  Changing the attributes of this
object will affect the size limits used by <a class="reference internal" href="#reprlib.repr" title="reprlib.repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> and the Python
debugger.</p>
</dd></dl>

<dl class="function">
<dt id="reprlib.repr">
<code class="sig-prename descclassname">reprlib.</code><code class="sig-name descname">repr</code><span class="sig-paren">(</span><em class="sig-param">obj</em><span class="sig-paren">)</span><a class="headerlink" href="#reprlib.repr" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the <a class="reference internal" href="#reprlib.Repr.repr" title="reprlib.Repr.repr"><code class="xref py py-meth docutils literal notranslate"><span class="pre">repr()</span></code></a> method of <code class="docutils literal notranslate"><span class="pre">aRepr</span></code>.  It returns a string
similar to that returned by the built-in function of the same name, but with
limits on most sizes.</p>
</dd></dl>

<p>In addition to size-limiting tools, the module also provides a decorator for
detecting recursive calls to <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__repr__()</span></code></a> and substituting a placeholder
string instead.</p>
<span class="target" id="index-0"></span><dl class="function">
<dt id="reprlib.recursive_repr">
<code class="sig-prename descclassname">&#64;</code><code class="sig-prename descclassname">reprlib.</code><code class="sig-name descname">recursive_repr</code><span class="sig-paren">(</span><em class="sig-param">fillvalue=&quot;...&quot;</em><span class="sig-paren">)</span><a class="headerlink" href="#reprlib.recursive_repr" title="Permalink to this definition">¶</a></dt>
<dd><p>Decorator for <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__repr__()</span></code></a> methods to detect recursive calls within the
same thread.  If a recursive call is made, the <em>fillvalue</em> is returned,
otherwise, the usual <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__repr__()</span></code></a> call is made.  For example:</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">reprlib</span> <span class="kn">import</span> <span class="n">recursive_repr</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">class</span> <span class="nc">MyList</span><span class="p">(</span><span class="nb">list</span><span class="p">):</span>
<span class="gp">... </span>    <span class="nd">@recursive_repr</span><span class="p">()</span>
<span class="gp">... </span>    <span class="k">def</span> <span class="fm">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="gp">... </span>        <span class="k">return</span> <span class="s1">&#39;&lt;&#39;</span> <span class="o">+</span> <span class="s1">&#39;|&#39;</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">map</span><span class="p">(</span><span class="nb">repr</span><span class="p">,</span> <span class="bp">self</span><span class="p">))</span> <span class="o">+</span> <span class="s1">&#39;&gt;&#39;</span>
<span class="gp">...</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">m</span> <span class="o">=</span> <span class="n">MyList</span><span class="p">(</span><span class="s1">&#39;abc&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">m</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">m</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">m</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="s1">&#39;x&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">print</span><span class="p">(</span><span class="n">m</span><span class="p">)</span>
<span class="go">&lt;&#39;a&#39;|&#39;b&#39;|&#39;c&#39;|...|&#39;x&#39;&gt;</span>
</pre></div>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.2.</span></p>
</div>
</dd></dl>

<section id="repr-objects">
<span id="id1"></span><h2>Repr Objects<a class="headerlink" href="#repr-objects" title="Permalink to this headline">¶</a></h2>
<p><a class="reference internal" href="#reprlib.Repr" title="reprlib.Repr"><code class="xref py py-class docutils literal notranslate"><span class="pre">Repr</span></code></a> instances provide several attributes which can be used to provide
size limits for the representations of different object types,  and methods
which format specific object types.</p>
<dl class="attribute">
<dt id="reprlib.Repr.maxlevel">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxlevel</code><a class="headerlink" href="#reprlib.Repr.maxlevel" title="Permalink to this definition">¶</a></dt>
<dd><p>Depth limit on the creation of recursive representations.  The default is <code class="docutils literal notranslate"><span class="pre">6</span></code>.</p>
</dd></dl>

<dl class="attribute">
<dt id="reprlib.Repr.maxdict">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxdict</code><a class="headerlink" href="#reprlib.Repr.maxdict" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxlist">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxlist</code><a class="headerlink" href="#reprlib.Repr.maxlist" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxtuple">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxtuple</code><a class="headerlink" href="#reprlib.Repr.maxtuple" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxset">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxset</code><a class="headerlink" href="#reprlib.Repr.maxset" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxfrozenset">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxfrozenset</code><a class="headerlink" href="#reprlib.Repr.maxfrozenset" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxdeque">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxdeque</code><a class="headerlink" href="#reprlib.Repr.maxdeque" title="Permalink to this definition">¶</a></dt>
<dt id="reprlib.Repr.maxarray">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxarray</code><a class="headerlink" href="#reprlib.Repr.maxarray" title="Permalink to this definition">¶</a></dt>
<dd><p>Limits on the number of entries represented for the named object type.  The
default is <code class="docutils literal notranslate"><span class="pre">4</span></code> for <a class="reference internal" href="#reprlib.Repr.maxdict" title="reprlib.Repr.maxdict"><code class="xref py py-attr docutils literal notranslate"><span class="pre">maxdict</span></code></a>, <code class="docutils literal notranslate"><span class="pre">5</span></code> for <a class="reference internal" href="#reprlib.Repr.maxarray" title="reprlib.Repr.maxarray"><code class="xref py py-attr docutils literal notranslate"><span class="pre">maxarray</span></code></a>, and  <code class="docutils literal notranslate"><span class="pre">6</span></code> for
the others.</p>
</dd></dl>

<dl class="attribute">
<dt id="reprlib.Repr.maxlong">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxlong</code><a class="headerlink" href="#reprlib.Repr.maxlong" title="Permalink to this definition">¶</a></dt>
<dd><p>Maximum number of characters in the representation for an integer.  Digits
are dropped from the middle.  The default is <code class="docutils literal notranslate"><span class="pre">40</span></code>.</p>
</dd></dl>

<dl class="attribute">
<dt id="reprlib.Repr.maxstring">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxstring</code><a class="headerlink" href="#reprlib.Repr.maxstring" title="Permalink to this definition">¶</a></dt>
<dd><p>Limit on the number of characters in the representation of the string.  Note
that the “normal” representation of the string is used as the character source:
if escape sequences are needed in the representation, these may be mangled when
the representation is shortened.  The default is <code class="docutils literal notranslate"><span class="pre">30</span></code>.</p>
</dd></dl>

<dl class="attribute">
<dt id="reprlib.Repr.maxother">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">maxother</code><a class="headerlink" href="#reprlib.Repr.maxother" title="Permalink to this definition">¶</a></dt>
<dd><p>This limit is used to control the size of object types for which no specific
formatting method is available on the <a class="reference internal" href="#reprlib.Repr" title="reprlib.Repr"><code class="xref py py-class docutils literal notranslate"><span class="pre">Repr</span></code></a> object. It is applied in a
similar manner as <a class="reference internal" href="#reprlib.Repr.maxstring" title="reprlib.Repr.maxstring"><code class="xref py py-attr docutils literal notranslate"><span class="pre">maxstring</span></code></a>.  The default is <code class="docutils literal notranslate"><span class="pre">20</span></code>.</p>
</dd></dl>

<dl class="method">
<dt id="reprlib.Repr.repr">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">repr</code><span class="sig-paren">(</span><em class="sig-param">obj</em><span class="sig-paren">)</span><a class="headerlink" href="#reprlib.Repr.repr" title="Permalink to this definition">¶</a></dt>
<dd><p>The equivalent to the built-in <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> that uses the formatting imposed by
the instance.</p>
</dd></dl>

<dl class="method">
<dt id="reprlib.Repr.repr1">
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">repr1</code><span class="sig-paren">(</span><em class="sig-param">obj</em>, <em class="sig-param">level</em><span class="sig-paren">)</span><a class="headerlink" href="#reprlib.Repr.repr1" title="Permalink to this definition">¶</a></dt>
<dd><p>Recursive implementation used by <a class="reference internal" href="#reprlib.Repr.repr" title="reprlib.Repr.repr"><code class="xref py py-meth docutils literal notranslate"><span class="pre">repr()</span></code></a>.  This uses the type of <em>obj</em> to
determine which formatting method to call, passing it <em>obj</em> and <em>level</em>.  The
type-specific methods should call <a class="reference internal" href="#reprlib.Repr.repr1" title="reprlib.Repr.repr1"><code class="xref py py-meth docutils literal notranslate"><span class="pre">repr1()</span></code></a> to perform recursive formatting,
with <code class="docutils literal notranslate"><span class="pre">level</span> <span class="pre">-</span> <span class="pre">1</span></code> for the value of <em>level</em> in the recursive  call.</p>
</dd></dl>

<dl class="method">
<dt>
<code class="sig-prename descclassname">Repr.</code><code class="sig-name descname">repr_TYPE</code><span class="sig-paren">(</span><em class="sig-param">obj</em>, <em class="sig-param">level</em><span class="sig-paren">)</span></dt>
<dd><p>Formatting methods for specific types are implemented as methods with a name
based on the type name.  In the method name, <strong>TYPE</strong> is replaced by
<code class="docutils literal notranslate"><span class="pre">'_'.join(type(obj).__name__.split())</span></code>. Dispatch to these methods is
handled by <a class="reference internal" href="#reprlib.Repr.repr1" title="reprlib.Repr.repr1"><code class="xref py py-meth docutils literal notranslate"><span class="pre">repr1()</span></code></a>. Type-specific methods which need to recursively
format a value should call <code class="docutils literal notranslate"><span class="pre">self.repr1(subobj,</span> <span class="pre">level</span> <span class="pre">-</span> <span class="pre">1)</span></code>.</p>
</dd></dl>

</section>
<section id="subclassing-repr-objects">
<span id="subclassing-reprs"></span><h2>Subclassing Repr Objects<a class="headerlink" href="#subclassing-repr-objects" title="Permalink to this headline">¶</a></h2>
<p>The use of dynamic dispatching by <a class="reference internal" href="#reprlib.Repr.repr1" title="reprlib.Repr.repr1"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Repr.repr1()</span></code></a> allows subclasses of
<a class="reference internal" href="#reprlib.Repr" title="reprlib.Repr"><code class="xref py py-class docutils literal notranslate"><span class="pre">Repr</span></code></a> to add support for additional built-in object types or to modify
the handling of types already supported. This example shows how special support
for file objects could be added:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">reprlib</span>
<span class="kn">import</span> <span class="nn">sys</span>

<span class="k">class</span> <span class="nc">MyRepr</span><span class="p">(</span><span class="n">reprlib</span><span class="o">.</span><span class="n">Repr</span><span class="p">):</span>

    <span class="k">def</span> <span class="nf">repr_TextIOWrapper</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">obj</span><span class="p">,</span> <span class="n">level</span><span class="p">):</span>
        <span class="k">if</span> <span class="n">obj</span><span class="o">.</span><span class="n">name</span> <span class="ow">in</span> <span class="p">{</span><span class="s1">&#39;&lt;stdin&gt;&#39;</span><span class="p">,</span> <span class="s1">&#39;&lt;stdout&gt;&#39;</span><span class="p">,</span> <span class="s1">&#39;&lt;stderr&gt;&#39;</span><span class="p">}:</span>
            <span class="k">return</span> <span class="n">obj</span><span class="o">.</span><span class="n">name</span>
        <span class="k">return</span> <span class="nb">repr</span><span class="p">(</span><span class="n">obj</span><span class="p">)</span>

<span class="n">aRepr</span> <span class="o">=</span> <span class="n">MyRepr</span><span class="p">()</span>
<span class="nb">print</span><span class="p">(</span><span class="n">aRepr</span><span class="o">.</span><span class="n">repr</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">stdin</span><span class="p">))</span>         <span class="c1"># prints &#39;&lt;stdin&gt;&#39;</span>
</pre></div>
</div>
</section>
</section>


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  <h3><a href="../contents.html">Table of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">reprlib</span></code> — Alternate <code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code> implementation</a><ul>
<li><a class="reference internal" href="#repr-objects">Repr Objects</a></li>
<li><a class="reference internal" href="#subclassing-repr-objects">Subclassing Repr Objects</a></li>
</ul>
</li>
</ul>

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